In the production of soluble coffee, a significant amount of commercially unacceptable dried coffee particles are produced. For example, conventional drying procedures, such as spray drying and freeze drying, result in the production of significant amounts of coffee fines, which typically have a particular size of less than about 0.5 mm, and are commercially undesirable. Such coffee fines usually are reprocessed so that while they are not included in commercial soluble coffee products, they are recovered to improve the economics of the production operation. That is, the coffee fines typically are added back to coffee liquor being processed in order to wet and dissolve the coffee particles in the liquor and thereby increase the total soluble solids level of the coffee liquor, which is recycled to the drying operation. However, because of their small particle size and hygroscopic character the coffee fines, when added to coffee liquor or other aqueous media, are difficult to wet and dissolve. The fine hygroscopic particles when contacted with coffee liquor or other aqueous media do not disperse but tend to form wet lumps having a gummy exterior surface and undissolved powder on the inside. In the past it has usually been necessary to heat the coffee liquor to an elevated temperature of about 90.degree. C. in order to effect wetting and dissolution of the fines in the viscous coffee liquor. However, heating of the coffee liquor to such elevated temperatures is detrimental to the quality of the resulting soluble coffee product. In addition, even with such heating, complete dissolution of the coffee fines could rarely be achieved in commercial operations due to the inability to break up and dissolve all of the lumps. Moreover, the addition of coffee fines to coffee liquor or other aqueous media tends to cause undesirable foaming due to the incorporation of entrained air. Consequently the apparatus and procedures which have been used heretofore for reprocessing coffee fines in concentrated coffee liquor have tended to produce very foamy, partially dissolved solutions containing relatively large amounts of wet powder lumps.